| 摘要 |
PURPOSE:To prevent secondary electrons and secondary ions and correctly measure the beam diameter by providing the second grid between the first grid projecting a convergent ion beam to be measured across its diameter and a Faraday cup. CONSTITUTION:A measuring device of the diameter of an ion beam used for the ion injection into a semi-conductor substrate or the like is formed by providing the second grid 22 having the second slit 22a and held at the negative potential against the ground potential between the first grid 21 having the first slit 21a and held at the positive potential against the ground potential and a Faraday cup 12. A convergent ion beam 60 is scanned on the surface of the first grid 21, and the beam diameter is measured with a measuring instrument 13. Accordingly, the secondary electron emission from the first grid 21 is eliminated, secondary ions are absorbed into the second grid 22, and only the ion beam 60 is allowed to flow into the Faraday cup 12 and can be correctly measured.
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